Many will find these scholastic explanations harder to accept than transubstantiation itself. The dogma is guaranteed by the Catholic Church. The explanations of the dogma lie beyond the domain alike of faith, of sensible experience, and of physical science. They rest on a structure of abstruse metaphysics, into which there enter elements much open to debate, as the 'principle of individuation.' At the same time, any one who will have it that transubstantiation is philosophically absurd, may well be asked whether he has mastered these scholastic subtleties, and has his reply ready to dispel them. All that a Catholic need care to do is to point out, as Newman does, how by reason of the very obscurity of the subject arguments against the possibility of transubstantiation cannot be cogent and apodictic. We are not bound to have forthcoming positive evidence of that possibility. We take the fact from the teaching of the Church, and leave the how to God. When physical science has said its last word on the constitution of matter; when psychology and metaphysics have finally disposed of substance and accident, 'things in themselves' and phenomena; we shall then be not quite so ill equipped as we are at present for speculating on the philosophy of transubstantiation.

Meanwhile, one important point seems to have escaped notice. Faith does not raise the question of any substance being converted into any other substance, but only of the substances of bread and wine being converted into the substance of the Body and Blood of Christ. Now the Body and Blood of Christ are the Body and Blood of God, and consequently hold a unique position among substances. God's Body may well 'supercomprehend,' so to speak, all lower material substances; and be able, after unseating any of them from the throne where it sits queen, surrounded by attendant accidents, itself occupy that same throne in the midst of those same accidents. We cannot safely conclude thereupon that any other material substance is capable of doing the like. It does not follow, to borrow St Thomas's own illustration, that because bread and wine can be changed into the Body and Blood of Christ, therefore, of my two fingers, one can be changed into the other. Of the intrinsic possibility of this latter conversion, -- and not even God can effect intrinsic impossibilities, -- I confess I entertain the gravest doubts. And Catholic faith allows me to doubt it. Vasquez (tom. 3, disp. 184) discusses an quaelibet res in quamlibet aliam converti possit.

Of God and His Creatures: 4.63